2. The animal kingdom extends far beyond
humans and other animals we may encounter
1.3 million living species of animals have been
identified
Invertebrates (animals that lack a backbone)
account for 95% of known animal species.
3. Most animals reproduce sexually, with the
diploid stage usually dominating the life cycle
After a sperm fertilizes an egg, the zygote
undergoes rapid cell division called cleavage
Cleavage leads to formation of a blastula
The blastula undergoes gastrulation, forming a
gastrula with different layers of embryonic
tissues.
6. Many animals have at least one larval stage.
A larva is sexually immature and
morphologically distinct from the adult; it
eventually undergoes metamorphosis.
7. Zoologists sometimes categorize animals
according to a body plan.
A body plan is a set of morphological and
developmental traits, integrated into a
functional whole living animal.
9. Animals can be categorized according to the
symmetry of their bodies, or lack of it
Some animals have radial symmetry
Two-sided symmetry is called bilateral
symmetry
10.
11. A dorsal (top) side and a ventral (bottom) side
A right and left side
Anterior (head) and posterior (tail) ends
13. Animal body plans also vary according to the
organization of the animal’s tissues
Tissues are collections of specialized cells
During development, three germ layers give
rise to the tissues and organs of the animal
embryo
14. Ectoderm is the germ layer covering the
embryo’s surface
Endoderm is the innermost germ layer and
lines the developing digestive tube, called the
archenteron
Mesoderm: middle layer of some body plans
15. Diploblastic animals have ectoderm and
endoderm
Triploblastic animals have an ectoderm,
endoderm and intervening mesoderm layer.
16. Most triploblastic animals possess a body cavity
A true body cavity is called a coelom and is
derived from mesoderm
Coelomates are animals that possess a true coelom
A pseudocoelom is a body cavity derived from the
mesoderm and endoderm
Triploblastic animals that possess a pseudocoelom
are called pseudocoelomates
Triploblastic animals that lack a body cavity are
called acoelomates
17.
18. Based on early development, many animals can
be categorized as having protostome
development or deuterostome development
19. These two types of developments differ in
regard to:
Different cleavage
Different coelom formation
Fate of the blastop
20. In protostome development, cleavage is spiral
and determinate
In deuterostome development, cleavage is
radial and indeterminate
With indeterminate cleavage, each cell in the
early stages of cleavage retains the capacity to
develop into a complete embryo
21.
22. In protostome development, the splitting of
solid masses of mesoderm forms the coelom.
In deuterostome development, the mesoderm
buds from the wall of the archenteron to form
the coelom.
23.
24. The blastopore forms during gastrulation and
connects the archenteron to the exterior of the
gastrula
In protostome development, the blastopore
becomes the mouth
In deuterostome development, the blastopore
becomes the anus
32. Sedentary animals (fixed in one position)
They live in both fresh and marine waters
Cellular level of development
Lack true tissues and organs
Asymmetrical
33. True tissue – Eumetazoa
Both sessile and motile forms including jellies,
corals, and hydras
Diploblastic body plan
Radial symmetry
The basic body plan of a cnidarian is a sac with
a central digestive compartment, the
gastrovascular cavity
A single opening functions as mouth and anus
34. Carnivores that use tentacles to capture prey
The tentacles are armed with cnidocytes,
unique cells that function in defense and
capture of prey
Nematocysts are specialized organelles within
cnidocytes that eject a stinging thread.
35. Live in marine, freshwater, and damp
terrestrial habitats.
Triploblastic development
Acoelomates
Flattened dorsoventrally and have a
gastrovascular cavity
Gas exchange takes place across the surface
Protonephridia regulate the osmotic balance
36. Found in most aquatic habitats, in the soil, in
moist tissues of plants, and in body fluids and
tissues of animals
They have an alimentary canal, but lack a
circulatory system
Sexual Reproduction
Internal fertilization
Some species are parasites of plants and
animals.
37. Bodies composed of a series of fused rings or
compartments - Metamerism
38. Found in nearly all habitats of the biosphere
The arthropod body plan consists of a
segmented body,
hard exoskeleton (made of layers of protein
and the polysaccharide chitin
jointed appendages
The body is completely covered by the cuticle
When it grows, it molts its exoskeleton.
Includes: insects, crabs, spiders, millipedes,
centipedes, mites
39.
40. Phylum Chordata consists of two subphyla of
invertebrates as well as hagfishes and
vertebrates
Vertebrates are a subphylum within the
phylum Chordata
Chordates are bilaterian animals that belong to
the Deuterostomia.
All chordates share a set of derived characters
Some species have some of these traits only
during embryonic development
